Hypothyroidism and Adverse Endpoints in Diabetic Patients: A Systematic Review and Meta-Analysis

Background: This study investigated the relationship strength between hypothyroidism and cardiovascular and renal outcomes in diabetic patients. Methods: The electronic databases PubMed, EmBase, and Cochrane library were screened for relevant studies published before November 2018. The outcomes included major cardiovascular events (MACEs), all-cause mortality, cardiac death, stroke, diabetic nephropathy (DN), diabetic retinopathy (DR), and chronic kidney disease (CKD). The pooled results for all outcomes were calculated using random-effects models. Results: A total of eight studies met the inclusion criteria. The summary results indicated that hypothyroidism was not associated with the risk of MACEs (OR:1.21; 95%CI:0.68–2.16; P = 0.514), all-cause mortality (OR:1.27; 95%CI:0.93–1.74; P = 0.136), cardiac death (OR:1.16; 95%CI:0.89–1.52; P = 0.271), stroke (OR:0.96; 95%CI: 0.49–1.88; P = 0.915), and DN (OR:1.71; 95%CI:0.37–7.90; P = 0.490). There was a significant association between hypothyroidism and the risk of DR (OR:1.73; 95%CI:1.08–2.77; P = 0.023) and CKD (OR:1.22; 95%CI:1.10–1.36; P < 0.001). Conclusions: These findings indicate that diabetic patients with hypothyroidism have an increased risk of DR and CKD. Additional large-scale prospective studies should be carried out to verify the prognosis of patients with diabetes and hypothyroidism.